Addition reaction of zinc acetylides to thioiminium salts leading to 3-amino-1-sulfenyl-1,4-enynes

The reaction of thioiminium salts with zinc acetylides took place at 60 °C to give 3-amino-1-sulfenyl-1,4-enynes in moderate to good yields. Two molecules of acetylides were incorporated into the products. Nucleophilic attack of zinc acetylides to thioiminium salts may initially occur to form alkynyl S,N-acetals, followed by their [1,3]-rearrangement to give 3-sulfenyl-1-aminoallenes.